1. Field of the Invention
This invention relates to capacitors and manufacturing method thereof, and in particular concerns connection of electrode terminals and electrodes of capacitor elements and a manufacturing method thereof.
2. Description of Related Art
Japanese Published Unexamined Application No.2002-134361 discloses capacitors having electrode terminals that respectively connect to a pair of electrodes of a capacitor element. FIG. 9 shows a sectional view of a conventional solid electrolytic capacitor. A solid electrolytic capacitor of related art is explained in this figure. The solid electrolytic capacitor shown in FIG. 9 comprises a capacitor element 105 that has an anode 101, a dielectric layer 102 formed on the anode 101, an electrolyte layer 103 formed on the dielectric layer 102, and a cathode 104 formed on the electrolyte layer 103.
The anode 101 includes an anode lead 101a and a plate-shaped base body 101b that is made of a porous sintered body such as tantalum particles and is formed to expose a part of the anode lead 101a on the anode lead 101a. 
The dielectric layer 102 is made from oxides such as tantalum oxide and is shaped to cover around the base body 101b. In addition, the dielectric layer 102 is formed by anodic oxidation of the anode 101.
The electrolyte layer 103 is made from manganese dioxide or conductive polymers such as polypyrrole and is shaped to cover around the dielectric layer 102.
The cathode 104 includes a first conductive layer 104a with compounds of carbon particles such as graphite, and is shaped to cover around the electrolyte layer 103, and a second conductive layer 104b with compounds of silver particles and is shaped to cover around the first conductive layer 104a. In addition, the first conductive layer 104a is formed by applying carbon paste to the electrolyte layer and drying the carbon paste. The second conductive layer 104b is formed by applying silver paste to the first conductive layer 104a and drying the silver paste.
A conductive adhesive layer 106 is formed on the upper surface of the cathode 104 of the capacitor element 105. The cathode 104 and cathode terminal 108 are connected through the conductive adhesive layer 106. By applying silver paste to the cathode 104 and drying the silver paste, the conductive adhesive layer 106 is formed of silver particles. Also, an anode terminal 109 is connected to the exposed anode lead 101a from the anode 101 by welding. In addition, a cathode terminal 108 and an anode terminal 109 are formed in nickel, copper and these alloys. In particularly, on the surface of the cathode terminal 108, which is connected to the cathode 104 of the capacitor element 105 through the conductive adhesive layer 106, a silver plating layer 108a is formed to improve adhesive properties of the conductive adhesive layer 106 and the cathode terminal 108.
Furthermore, a mold resin 110 is formed around the capacitor element 105, the cathode terminal 108, and the anode terminal 109 so as to expose an end of both the cathode terminal 108 and the anode terminal 109 to the outside.
However, in a conventional solid electrolytic capacitor as described above, contact resistance between the conductive adhesive layer 106 and the cathode terminal 108 becomes high. Further, the equivalent series resistance (ESR) becomes particularly high at high frequencies.